The Effect of Humidity on the Stability of LTCC Pressure Sensors

2012 ◽  
Vol 19 (1) ◽  
pp. 133-140 ◽  
Author(s):  
Marina Zarnik ◽  
Darko Belavic
Keyword(s):  
Pressure Sensors ◽  
Low Pressure ◽  
Numerical Analyses ◽  
Capacitive Sensors ◽  
Differential Mode ◽  
Piezoresistive Sensors ◽  
Mode Of Operation ◽  
The Stability

The Effect of Humidity on the Stability of LTCC Pressure SensorsLTCC-based pressure sensors are promising candidates for wet-wet applications in which the effect of the surrounding media on the sensor's characteristics is of key importance. The effect of humidity on the sensor's stability can be a problem, particularly in the case of capacitive sensors. A differential mode of operation can be a good solution, but manufacturing the appropriate sensing capacitors remains a major challenge. In the case of piezoresistive sensors the influence of humidity is less critical, but it still should be considered as an important parameter when designing sensors for low-pressure ranges. In this paper we discuss the stability of the sensors' offset characteristics, which was inspected closely using experimental and numerical analyses.

scholarly journals Flexible Ecoflex®/Graphene Nanoplatelet Foams for Highly Sensitive Low-Pressure Sensors

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4406
Author(s):  
Marco Fortunato ◽  
Irene Bellagamba ◽  
Alessio Tamburrano ◽  
Maria Sabrina Sarto
Keyword(s):  
High Performance ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Cost Effective ◽  
Low Pressure ◽  
Human Motion ◽  
Compression Tests ◽  
Piezoresistive Sensors ◽  
Human Motion Detection ◽  
Pressure Regime

The high demand for multifunctional devices for smart clothing applications, human motion detection, soft robotics, and artificial electronic skins has encouraged researchers to develop new high-performance flexible sensors. In this work, we fabricated and tested new 3D squeezable Ecoflex® open cell foams loaded with different concentrations of graphene nanoplatelets (GNPs) in order to obtain lightweight, soft, and cost-effective piezoresistive sensors with high sensitivity in a low-pressure regime. We analyzed the morphology of the produced materials and characterized both the mechanical and piezoresistive response of samples through quasi-static cyclic compression tests. Results indicated that sensors infiltrated with 1 mg of ethanol/GNP solution with a GNP concentration of 3 mg/mL were more sensitive and stable compared to those infiltrated with the same amount of ethanol/GNP solution but with a lower GNP concentration. The electromechanical response of the sensors showed a negative piezoresistive behavior up to ~10 kPa and an opposite trend for the 10–40 kPa range. The sensors were particularly sensitive at very low deformations, thus obtaining a maximum sensitivity of 0.28 kPa−1 for pressures lower than 10 kPa.

scholarly journals Study on the Stability of the Electrical Connection of High-Temperature Pressure Sensor Based on the Piezoresistive Effect of P-Type SiC

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 216
Author(s):  
Yongwei Li ◽  
Ting Liang ◽  
Cheng Lei ◽  
Qiang Li ◽  
Zhiqiang Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
Extreme Environment ◽  
Maximum Temperature ◽  
Piezoresistive Effect ◽  
Electrical Connection ◽  
Contact Stability ◽  
The Stability ◽  
P Type

In this study, a preparation method for the high-temperature pressure sensor based on the piezoresistive effect of p-type SiC is presented. The varistor with a positive trapezoidal shape was designed and etched innovatively to improve the contact stability between the metal and SiC varistor. Additionally, the excellent ohmic contact was formed by annealing at 950 °C between Ni/Al/Ni/Au and p-type SiC with a doping concentration of 1018cm−3. The aging sensor was tested for varistors in the air of 25 °C–600 °C. The resistance value of the varistors initially decreased and then increased with the increase of temperature and reached the minimum at ~450 °C. It could be calculated that the varistors at ~100 °C exhibited the maximum temperature coefficient of resistance (TCR) of ~−0.35%/°C. The above results indicated that the sensor had a stable electrical connection in the air environment of ≤600 °C. Finally, the encapsulated sensor was subjected to pressure/depressure tests at room temperature. The test results revealed that the sensor output sensitivity was approximately 1.09 mV/V/bar, which is better than other SiC pressure sensors. This study has a great significance for the test of mechanical parameters under the extreme environment of 600 °C.

scholarly journals ANALYSIS OF CYBER RESISTANCE ASSESSMENT METHODS OF CRITICAL INFRASTRUCTURE

2021 ◽  
Vol 12 (4) ◽  
pp. 29-35
Author(s):  
Irina Maltseva ◽  
Yuliya Chernysh ◽  
Viacheslav Ovsiannikov
Keyword(s):  
Law Enforcement ◽  
Critical Infrastructure ◽  
Infrastructure Management ◽  
Automated Control ◽  
Sustainable Operation ◽  
Mode Of Operation ◽  
Common Resource ◽  
The Stability ◽  
Definition Of ◽  
Infrastructure Stability

The availability of critical infrastructure through cyberspace makes national security dependent on the degree of its security. Critical infrastructure is a set of automated management systems, which provide the interaction of information and telecommunications networks that solve problems of public administration, defense, security and law enforcement, and others. The protection of critical infrastructure directly depends on the possession of the relevant structures of new weapons, the degree of its effectiveness, methods of use and means of protection against the same weapons of the enemy. It is necessary to address the issue of effective confrontation in cyberspace. The analysis of problems in the development of methods for assessing the functional stability of critical infrastructure in cyber confrontation requires the definition of basic methods and criteria that can be used in Ukraine to assess the stability of critical infrastructure. Cyber weapons, which carry out destructive information effects, are not weapons in the classical sense, because they do not physically damage the object of attack, but translate its information and automated control systems into a crisis mode of operation. The process of counteraction of two or more parties, in this form, is a cyber confrontation that is realized using a common common resource - the global information space. In the process of critical infrastructure management, cyber confrontation imposes additional requirements to ensure the sustainable operation of critical infrastructure. Stability is an integral property that is inextricably linked to the operating environment. Cyber resilience is an integrated indicator and is determined by cyber reliability, which reflects the ability to perform its tasks in a complex critical infrastructure management system in the context of information destructive influences.

Stability of a Piezoresistive Ceramic Pressure Sensor Made With LTCC Technology

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000371-000376 ◽  
Author(s):  
Marina Santo Zarnik ◽  
Darko Belavic
Keyword(s):  
Pressure Sensor ◽  
Fatigue Testing ◽  
Low Pressure ◽  
Fatigue Tests ◽  
Point Of View ◽  
Long Term Stability ◽  
Pressure Cycling ◽  
Key Characteristics ◽  
The Stability

This paper discusses the stability of a piezoresistive, LTCC-based, pressure sensor that was designed for measurements in a low-pressure range below 100 mbar. The intrinsic stability of the sensor's offset was evaluated at a constant ambient temperature and different conditions regarding the atmospheric humidity. The sensors were also subjected to functional fatigue tests, which included a full-scale and an overload pressure cycling. The results of the fatigue testing revealed the vulnerability of the sensor's structure from the point of view of the long-term stability and the life-cycle. Nevertheless, the stability of the key characteristics of the prototype sensors was found to be satisfactory for accurate measurements in the low-pressure ranges.

Stall inception mechanisms in a contra-rotating fan operating at different speed combinations

2019 ◽  
Vol 234 (8) ◽  
pp. 1041-1052 ◽  
Author(s):  
MP Manas ◽  
AM Pradeep
Keyword(s):  
Pressure Ratio ◽  
Pressure Sensors ◽  
Stability Limit ◽  
Leading Edge ◽  
Axial Direction ◽  
Tip Leakage Flow ◽  
Stall Inception ◽  
Unsteady Pressure ◽  
Stall Cells ◽  
The Stability

Contra-rotating fan is a concept that can possibly replace the present-day conventional fans due to its several aerodynamic advantages. It has the potential to improve the stability limit and can achieve a higher pressure ratio per stage. One of the advantages of a contra-rotating fan is its capability to operate both the rotors at different speeds. In the present study, experiments are carried out at different speed combinations of the rotors and the stall inception phenomenon is captured using high-response unsteady pressure sensors placed on the casing upstream of the leading edge of rotor-1. The unsteady pressure data are investigated using wavelet and Fourier analysis techniques. It is observed that the mechanism of stall inception is different for different speed combinations. The pre-stall disturbances fall in different frequency ranges for different speed combinations. For the range of speed combinations investigated, the frequency of appearance of stall cells of rotor-1 does not depend on the speed of rotor-2. A higher speed of rotation of rotor-1 leads to a higher frequency of appearance of stall cells and a lower speed of rotation of rotor-1 leads to a lower frequency of appearance of stall cells. For all the speed combinations, there is a range of frequency where no disturbance is observed and this range is termed as the ‘no-disturbance zone’. Disturbances are observed at lower frequencies and at frequencies close to the blade passing frequency. In order to understand the flow physics in detail, computational analysis is carried out for different speed combinations of the rotors. For a higher speed of rotor-2, it is observed that the suction effect of rotor-2 is significant enough to pull the tip-leakage flow towards the axial direction. Thus, the suction effect of rotor-2 plays a significant role in determining the stall of the stage.

scholarly journals Design, Manufacture and Testing of Capacitive Pressure Sensors for Low-Pressure Measurement Ranges

Micromachines ◽  
2017 ◽  
Vol 8 (2) ◽  
pp. 41 ◽  
Author(s):  
Vasileios Mitrakos ◽  
Lisa Macintyre ◽  
Fiona Denison ◽  
Philip Hands ◽  
Marc Desmulliez
Keyword(s):  
Pressure Measurement ◽  
Pressure Sensors ◽  
Low Pressure

Stability Increase of Aerodynamically Unstable Rotors Using Intentional Mistuning

2006 ◽  
Author(s):  
Carlos Martel ◽  
Roque Corral ◽  
Jose´ Miguel Llorens
Keyword(s):  
Asymptotic Expansion ◽  
Small Parameter ◽  
Structural Dynamics ◽  
Low Pressure ◽  
Vibration Characteristics ◽  
Stability Properties ◽  
First Order ◽  
Low Pressure Turbine ◽  
Turbine Rotors ◽  
The Stability

A new simple asymptotic mistuning model (AMM), which constitutes an extension of the well known Fundamental Mistuning Model for groups of modes belonging to a modal family exhibiting a large variation of the tuned vibration characteristics, is used to analyze the effect of mistuning on the stability properties of aerodynamically unstable rotors. The model assumes that both, the aerodynamics and the structural dynamics of the assembly are linear, and retains the first order terms of a fully consistent asymptotic expansion of the tuned system where the small parameter is the blade mistuning. The simplicity of the model allows the optimization of the blade mistuning pattern to achieve maximum rotor stability. The results of the application of this technique to realistic welded-in-pair and interlock low-pressure-turbine rotors are also presented.

scholarly journals Highly-Sensitive Textile Pressure Sensors Enabled by Suspended-Type All Carbon Nanotube Fiber Transistor Architecture

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1103
Author(s):  
Jae Sang Heo ◽  
Keon Woo Lee ◽  
Jun Ho Lee ◽  
Seung Beom Shin ◽  
Jeong Wan Jo ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Pressure Sensor ◽  
Pressure Range ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Low Pressure ◽  
Electronic Textiles ◽  
Carbon Nanotube Fiber ◽  
Cnt Fiber ◽  
Walled Carbon Nanotubes

Among various wearable health-monitoring electronics, electronic textiles (e-textiles) have been considered as an appropriate alternative for a convenient self-diagnosis approach. However, for the realization of the wearable e-textiles capable of detecting subtle human physiological signals, the low-sensing performances still remain as a challenge. In this study, a fiber transistor-type ultra-sensitive pressure sensor (FTPS) with a new architecture that is thread-like suspended dry-spun carbon nanotube (CNT) fiber source (S)/drain (D) electrodes is proposed as the first proof of concept for the detection of very low-pressure stimuli. As a result, the pressure sensor shows an ultra-high sensitivity of ~3050 Pa−1 and a response/recovery time of 258/114 ms in the very low-pressure range of <300 Pa as the fiber transistor was operated in the linear region (VDS = −0.1 V). Also, it was observed that the pressure-sensing characteristics are highly dependent on the contact pressure between the top CNT fiber S/D electrodes and the single-walled carbon nanotubes (SWCNTs) channel layer due to the air-gap made by the suspended S/D electrode fibers on the channel layers of fiber transistors. Furthermore, due to their remarkable sensitivity in the low-pressure range, an acoustic wave that has a very tiny pressure could be detected using the FTPS.

scholarly journals A Hollow Stiffening Structure for Low Pressure Sensors

2009 ◽  
Vol 1 (1) ◽  
pp. 100-103
Author(s):  
P.K. Kinnell ◽  
J. King ◽  
M. Lester ◽  
R. Craddock
Keyword(s):  
Pressure Sensors ◽  
Low Pressure

scholarly journals Biochemical piezoresistive sensors based on pH- and glucose-sensitive hydrogels for medical applications

2016 ◽  
Vol 2 (1) ◽  
pp. 117-121 ◽  
Author(s):  
Ulrike Schmidt ◽  
Margarita Guenther ◽  
Gerald Gerlach
Keyword(s):  
Pressure Sensors ◽  
Glucose Monitoring ◽  
Biological Species ◽  
Detection Sensitivity ◽  
Tetraethylene Glycol ◽  
Piezoresistive Sensors ◽  
Piezoresistive Pressure Sensor ◽  
Set Up ◽  
Reversible Gel ◽  
Piezoresistive Pressure Sensors

AbstractMany conventional analysis techniques to detect chemical or biological species are able to achieve a high detection sensitivity, however, they are equipment- or time-expensive due to a multi-step procedure. In this work we describe sensor concepts using piezoresistive pressure sensor chips with integrated analyte-sensitive hydrogels, that enable inexpensive and robust biochemical sensors which are miniaturizable and in-line capable. Biocompatible hydrogels were developed and tested for pH- and glucose-monitoring during the chemical and biochemical processes. For that, monomer mixtures based on hydroxypropyl methacrylate HPMA, 2-(dimethylamino)ethyl methacrylate DMAEMA, tetraethylene glycol dimethacrylate TEGDMA and ethylene glycol EG were photo-polymerized. By means of carbodiimide chemistry, glucose oxidase was bound to the pH-sensitive HPMA/DMAEMA/TEGDMA/EG hydrogel squares causing the glucose-sensitivity. The crosslinked hydrogels were integrated in piezoresistive pressure sensors of different designs. pH- and glucose-depending reversible gel swelling processes were observed by means of the output voltage of dip sensors and of a novel implantable flexible sensor set-up. Due to its biocompatible components, the latter could be used inside the human body monitoring physiological blood values, for example glucose.

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